Vibrational entropy of L1[sub 2] Cu[sub 3]Au measured by inelastic neutron scattering
- Keck Laboratory of Engineering Materials, mail 138-78, California Institute of Technology, Pasadena, California 91125 (United States)
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
The phonon density of states of elemental Au, Cu, and Cu[sub 3]Au with L1[sub 2] chemical order were measured by inelastic neutron scattering and used to calculate the vibrational entropy of formation of the ordered compound from the elemental metals. A vibrational entropy of formation of (0.06[plus minus]0.03) hthinsp;k[sub B]/atom at 300 K was obtained, with the vibrational entropy of the ordered alloy being larger than that of the elemental metals. The phonon DOS of the disordered Cu[sub 3]Au was simulated by adding the phonon DOS curves of fcc Cu, L1[sub 2] hthinsp;Cu[sub 3]Au, and fcc Au to match the numbers of first-nearest-neighbor pairs in a disordered alloy. The vibrational entropy obtained with this simulated DOS disagrees with calorimetric data and theoretical estimates, indicating that the phonon DOS of disordered Cu[sub 3]Au depends on chemical order at spatial lengths larger than is set by first-nearest-neighbor pairs. [copyright] [ital 1999] [ital The American Physical Society]
- OSTI ID:
- 6448025
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 60:6; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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COPPER
COPPER ALLOYS
ENERGY-LEVEL DENSITY
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GOLD
GOLD ALLOYS
NEUTRON DIFFRACTION
PHONONS
VIBRATIONAL STATES
ALLOYS
COHERENT SCATTERING
DIFFRACTION
ELEMENTS
ENERGY
ENERGY LEVELS
EXCITED STATES
METALS
PHYSICAL PROPERTIES
QUASI PARTICLES
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THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties